The monolithic network architecture of 2nd generation mobile communications networks (so-called 2G systems) is well known. E.g., the non-layered architecture for a Group Special Mobile GSM circuit switched core network comprises a Mobile Switching Centre MSC/VLR that is connected via the so-called A-interface to the radio access network and via the so-called Lg interface to the further core network of the communications system. The MSC/VLR performs switching tasks in the 2G network. To do so, it processes user data and signalling data, both of which are exchanged with the radio access network by means of the so-called A-interface.
A layered network architecture has been developed for 3rd generation mobile communications systems (so-called 3G systems), e.g. used for the wideband code divisional multiple access WCDMA based Universal Mobile Telecommunications Systems UMTS. The split architecture provides a control plane for the handling of signalling data and a separate user plane for the: handling of user data. Consequently, the MSC/VLR node is being replaced in the split architecture by a MSC-Server in the control plane and a Media-Gateway MGW in the user plane. The MSC-Server processes signalling data related to switching tasks, while the Media-Gateway processes user data related switching tasks. WO 01/13657 A1 refers to an implementation of call setup procedures with separation of call control and bearer control.
Architectural details can be found in the following specifications issued by the 3GPP organisation: 3GPP 23.002 version 5.6 Network Architecture, in particular chapter 4.1.2; and 3GPP 23.205 version 5.1 Bearer-independent circuit-switched core network, in particular in chapter 5.1 for the logical architecture.
In order to provide subscribers with the enhanced services of UMTS, network operators will migrate their networks during a transition period of some years towards the split architecture. However, a lot of operators have certain spare capacity within their GSM networks, and would like to use it to handle WCDMA traffic instead of buying new MSC-Server nodes. In order to achieve this, the operator would need to configure the existing MSC nodes as MSC servers and then move all the existing GSM traffic to remote MGWs. However, this drastic migration would disrupt the existing GSM traffic.
Therefore, it is an object of the invention to provide an improved switching node of a communications system and an improved method to control the operation of a switching node of a communications system, which allow for a smooth migration from non-split to split architecture and at the same time allow for minimizing the investments into physical equipments.